It is found that a soldering tool using gases as fuel has been widely used, for instance, heating painted surfaces to affect scraping, and by thermal expansion of PVC to facilitate the engagement of pipe joints, to loosen nuts from bolts. Though conventional devices (including two U.S. Pat. Nos. 5,007,405 and No. 4,858,593 granted to the same inventor) can be applied, the structure thereof still has room for improvement, for example, improving the air intake and the cooling of the combustion tip to reduce the possibility of injury by heat, and prevent the soldering tool from becoming opened and raise the working performance. Thus the function of this soldering tool will be an improvement over present arts.